Page size issue PDF creation of barcodes using reportlab

Question

Okay i created a script today that takes an item# or any number for that purpose to generate a barcode. Now i wanted to print 60 same barcodes in 4 columns, that would make it a matrix of (15 X 4) only making it easy to understand. Now i successfully achieved it with a custom sized page (900*850) and fitted in 15 rows and 4 columns of barcodes generated by reportlab code128.

Here is the code:

from reportlab.graphics.barcode import code128
from reportlab.lib.units import mm
from reportlab.pdfgen import canvas

#----------------------------------------------------------------------#
def createBarCodes():
    codeName = "NOT_C17"

    c = canvas.Canvas(codeName+".pdf")
    c.setPageSize((900, 850))

    barcode_value = codeName
    barcode128 = code128.Code128(
                            barcode_value,
                            barHeight=20,
                            barWidth=1.05,
                            fontSize=15,
                            humanReadable = True
                        )

    x = 15 * mm
    for i in range(4):
        y = 275 * mm
        i=0
        while i < 15:
            barcode128.drawOn(c, x, y)
            y = y - 18 * mm
            i+=1
        x=x+(70*mm)
    c.save()

if __name__ == "__main__":
    createBarCodes()

A file generated by this script

The issue is that now I am restricted to using only US Letter size and no other custom size. I tried few variations but none worked.

Tries:

from reportlab.lib.pagesizes import letter
c = canvas.Canvas(codeName+".pdf", pagesize=letter)

barcode_value = codeName
barcode128 = code128.Code128(
                          barcode_value,
                          barHeight=16.7564*mm,
                          barWidth=44.45*mm,
                          fontSize=15,
                          humanReadable = True
                     )

x = 7.526 * mm
for i in range(4):
    y = 265.524 * mm
    i=0
    while i < 15:
        barcode128.drawOn(c, x, y)
        y = y - 18 * mm
        i+=1
        break
    x=x+(70*mm)
    break
c.save()

and here is the required format that it must fit in. Would be nice to have to help.

Answer 1

You code requires a lot of improvement

1. Use the letter size from reportlab.lib.pagesizes import letter

2. Set your margins and other variables as specified in the document :

   margin_x        =  7.526
   margin_y        =  13.876
   padding_x       =  7.526
   font_size       =  15
   width, height   =  letter
   

3. Calculate the total size of the generated codebar

   bars_width   = (float(width-margin_x*2)-3*padding_x)/4
   bars_height  = float(height-margin_y*2)/15
   

4. The width value passed to the function Code128 is the width of a single bar within the codebar and not the whole codebar, you should keep this value below 1.1

   bar_height   = bars_height - font_size
   bar_width    = 1
   

5. your loops would be better this way :

   for i in range(0,4):
       for j in range(0,15):
           x = margin_x + i * (bars_width+padding_x)
           y = margin_y + j * bars_height
           barcode128.drawOn(c, x , y)
   

6. this is the final script :

   from reportlab.graphics.barcode import code128
   from reportlab.lib.units import mm
   from reportlab.pdfgen import canvas
   from reportlab.lib.pagesizes import letter
   
   #----------------------------------------------------------------------#
   def createBarCodes():
       codeName = "NOT_C17"
   
       c = canvas.Canvas(codeName+".pdf",pagesize=letter)
   
       margin_x        =  7.526
       margin_y        =  13.876
       padding_x       =  7.526
       font_size       =  15
       width, height   =  letter
       extra_padding   =  20
   
       bars_width   = (float(width-margin_x*2)-3*padding_x)/4
       bars_height  = float(height-margin_y*2)/15
   
       bar_height   = bars_height - font_size
       #For alphanumeric values, the total number of bars is calculated as:
       #total = (11*string_length+35)
       bar_width    = (bars_width-extra_padding)/(len(codeName)*11+35)
   
   
       barcode_value = codeName
       barcode128 = code128.Code128(
                               barcode_value,
                               barHeight=bar_height,
                               barWidth=bar_width,
                               humanReadable = True
                           )
   
       for i in range(0,4):
           for j in range(0,15):
               x = margin_x + i * (bars_width+padding_x)
               y = margin_y + j * bars_height
               barcode128.drawOn(c, x , y)
   
       c.save()
   
   if __name__ == "__main__":
       createBarCodes()